class C_A 
{
private:
  int a_;
  
public:
  C_A() { a_ = 0; };
  void A_M_a () { a_++; };
};

class C_B : public C_A
{
public:
  void B_M_a() { A_M_a (); };
};

class C_C : public C_B
{
public:
  void C_M_a() { B_M_a(); };
};

int main()
{

  C_C val;

  val.A_M_a();

  return 0;
}
